Dimer Research Papers - Academia.edu (original) (raw)

In this work, three new pharmaceutical hydrated salts of ciprofloxacin with selected derivatives of benzoic acid, namely 4-hydroxybenzoic acid, 4-aminobenzoic acid and gallic acid, were obtained and systematically investigated by several... more

In this work, three new pharmaceutical hydrated salts of ciprofloxacin with selected derivatives of benzoic acid, namely 4-hydroxybenzoic acid, 4-aminobenzoic acid and gallic acid, were obtained and systematically investigated by several solid-state analytical techniques. In situ Raman spectroscopy was applied to elucidate the alternative pathways of the solid forms' formation under mechanochemical conditions. Crystal structure analysis and a CSD survey allowed us to establish a distinct supramolecular motif formed by infinite columnar stacks of ciprofloxacin dimers arranged in the "head-to-tail" manner. An alternative "head-to-head" packing arrangement was only observed in the crystal of the hydrated ciprofloxacin salt with 4-aminobenzoic acid. In addition, the pH-solubility behavior of the solid forms was thoroughly investigated. Furthermore, a distinct structure-property relationship between the specific features of the supramolecular organization of the hydrated salts and their solubility was observed and discussed.

Photoreceptors are a class of light-sensing proteins with critical biological functions. UVR8 is the only identified UV photoreceptor in plants and its dimer dissociation upon UV sensing activates UV-protective processes. However, the... more

Photoreceptors are a class of light-sensing proteins with critical biological functions. UVR8 is the only identified UV photoreceptor in plants and its dimer dissociation upon UV sensing activates UV-protective processes. However, the dissociation mechanism is still poorly understood. Here, by integrating extensive mutations, ultrafast spectroscopy, and computational calculations, we find that the funneled excitation energy in the interfacial tryptophan (Trp) pyramid center drives a directional Trp-Trp charge separation in 80 ps and produces a critical transient Trp anion, enabling its ultrafast charge neutralization with a nearby positive arginine residue in 17 ps to destroy a key salt bridge. A domino effect is then triggered to unzip the strong interfacial interactions, which is facilitated through flooding the interface by channel and interfacial water molecules. These detailed dynamics reveal a unique molecular mechanism of UV-induced dimer monomerization.

Pregnant women appear to be more severely affected by COVID-19. Coagulopathy is known as one of the most challenging effects of COVID-19, and the effects of acute airway diseases resulting from the coronavirus on pregnant mothers and... more

Pregnant women appear to be more severely affected by COVID-19. Coagulopathy is known as one of the most challenging effects of COVID-19, and the effects of acute airway diseases resulting from the coronavirus on pregnant mothers and their fetuses can be dangerous. Two women who were pregnant suffering from coagulopathy (one of them with disseminated intravascular coagulation (DIC) and the other one with hypercoagulation) and COVID-19 infection are reported in this study. During hospitalization due to severe vaginal bleeding and placental detachment, cesarean section was performed on the first case and because of acute severe DIC, she received a massive transfusion. The second patient presented with epigastric pain and tachycardia and positive D-dimer, which was eventually treated with a diagnosis of bilateral lower extremities DVT. COVID-19 might have a variety of effects on pregnancy outcome, from vascular and placental involvement to respiratory involvement; there is an association between the coronavirus and hyper-coagulopathy state and coagulopathy like DIC.

The hypercoagulability, thromboembolic and endothelial complications associated with hemoglobinopathies often results in vascular blockage and occasionally death; which has, therefore, become a challenge to the physician over time. This... more

The hypercoagulability, thromboembolic and endothelial complications associated with hemoglobinopathies often results in vascular blockage and occasionally death; which has, therefore, become a challenge to the physician over time. This study aimed at evaluating the protective effects of a polyherbal formulation on endothelial dysfunction, venous thrombosis, coagulation indices; D-dimer and inflammation using 2-butoxyethanol (2BE)-induced experimental model of thrombosis and vaso-occlusive disorders in female albino rats. Forty-two (42) healthy twelve-week old female albino rats were randomly selected for this study and divided into six groups, the rats were administered 2.5mL/kg of 2-BE p.o. and 1mL/Kg of 100mg/mL polyherbal formula for 15 days respectively pre-and post-2-BE administration. The levels of coagulation indices, D-dimer and inflammation marker were thereafter evaluated. Histological assessment of the liver was used to evaluate the expression of microvascular occlusion and ischemia. Polyherbal formulation treatment significantly (p<0.05) reduced circulating D-dimer and C-reactive protein levels, as well as the platelet dyscrasias, associated endothelial dysfunction and venous thrombosis in the vessels by decreasing the levels of coagulation indices of the treated groups. There was also down-regulation of the expression of tissue necrosis in the liver of rats treated with 2-BE as a result of Polyherbal treatment. The polyherbal formula, therefore, shows potential for use in the management of conditions associated with thrombotic, thromboembolic disorders and the associated endothelial dysfunction. Molecular investigation of the bioactive components is however expedient to better understand the specific mechanisms of action.

Insulin receptor (IR) and epidermal growth factor receptors (EGFR) are members of the receptor tyrosine kinase super family. The extracellular regions of both IR and EGFR contain two L domains. Many crystal structures of the extracellular... more

Insulin receptor (IR) and epidermal growth factor receptors (EGFR) are members of the receptor tyrosine kinase super family. The extracellular regions of both IR and EGFR contain two L domains. Many crystal structures of the extracellular regions of the IR and EGFR families have been determined in both the unliganded state and in complexes with ligands. The structures reveal that the L domains consist of four to six leucine rich repeats (LRRs); although, their amino acid sequences are highly variable. The present bioinformatic analysis reveals some features on the LRRs and the structures. We conclude that the LRRs in the L domains belong to a non-canonical motif differing from the known (canonical) motifs; the repeat units consist of two β-strands and the overall shape of the LRRs resembles a prism. To characterize the spatial arrangement of the two L-domains we propose two parameters; the distance between the two L domains (D) and the angle between the two axes showing the direction of the β-sheet stacking of the LRRs in the L domains (Ψ). These two parameters, D and Ψ, describe an essential feature of the structures and ligand induced structural changes.